1. Field of the Invention
This invention relates in general to devices for facilitating breathing and artificial respiration and in particular to a new and useful device for connection to the trachea of an infant for supporting human breathing or artificial respiration.
2. Description of the Prior Art
In many cases, particularly in diseases of newborn, especially prematurely born, infants, it is necessary to support the breathing or even to have recourse to an artificial respiration. One of the most frequent diseases of newborn infants is the "hyalone-membrane disease" of the lungs where the alveoli collapse because of the high surface tension at a low transpulmonary pressure (i.e. pressure at the respiratory opening minus pleura pressure). This pathophysiological state results in a serious disease aspect and may lead up to a stop of the spontaneous breathing. The therapy in such cases consists in preventing the collapse of the alveoli by an increased transpulmonary pressure. For this purpose, the pressure of the air supplied to the patient is increased to a constant value amounting to between 10 and 150 mm water column, about 50 mm water column on the average, depending on the constitution of the patient. This method is known in the medical practice as the "Continuous Positive Airway Pressure" (CPAP). At a stop of the spontaneous respiration, a mechanical circulation of air is used in which the pressure is periodically varied in accordance with the breathing rhythm. The pressure used in the CPAP is the lower limit of the pressure and during the inspiration period, this pressure is increased to a value necessary for inflating the lungs.
The present invention relates to a device for supporting human breathing and/or artificial respiration, in particular, of prematurely born, newborn and sucking infants, with which the pressure of the breathing gas to be supplied to the lungs can be increased and/or varied in accordance with the respiratory rhythm. The device includes a tracheal tube which is connectable to the trachea and which communicates with a space adapted to be pressurized. The known devices of this kind use a static pressure which is built up in a closed space. This space communicates with the tracheal tube which is inserted into the trachea of the patient and thus connected as tightly as possible therewith. At the application of the CPAP, the necessary constant pressure is maintained in this closed space. This space is connected to the pressure source for the breathing gas which, usually, consists of air enriched with oxygen, and further connected, through a pressure-maintaining valve which, usually, simply comprises a pipe immerged to a corresponding depth below the surface of a water reservoir, to the outer atmosphere. Thus, the breathing gas flows through this space and the expiration gas escapes through the pressure-maintaining valve. Although new, fresh breathing gas is permanently supplied to this space, the dead space is still considerable so that there is a danger, particularly for prematurely born infants, that the patient will inhale stale breathing gas. Known devices of this kind simply comprise a T tube of which one leg is connected to a tracheal tube, the second leg to the supply line for the breathing gas and the third leg to the pressure-maintaining valve. Usually, the perpendicular leg of the T is connected to the tracheal tube and the aligned cross legs are connected to the supply line for the breathing gas and the pressure-maintaining valve, respectively. For purposes of artificial respiration, a valve may be provided which is moved in accordance with the breathing rhythm and establishes the connection, during the inspiration period, between the tracheal tube and the supply line for the breathing gas and, during the expiration period, between the tracheal tube and the pressure-maintaining valve. Aside from the fact that such known devices are complicated and, therefore, expensive, they have the disadvantage that during the use of the device, the tracheal tube is not accessible, since the static pressure must be built up in a closed space. Now, it is necessary to periodically remove mucus by suction and for this purpose, the apparatus must be disconnected and the treatment interrupted which may lead to serious medical complications. Further, the known devices are also susceptible to disturbances. If, for example, the tube leading to the pressure-maintaining valve forms a kink, which may happen time and again, the static pressure in the space continues to linearly increase which may lead to a bursting of the lungs, thus being fatal to the patient. If the supply tube for the breathing gas forms a kink or becomes disconnected, breathing gas is no longer supplied and there is danger of asphyxiation. If, with an artificial respiration, the valve or the valve control fails, then, depending on the position of the valve, in case the tracheal tube remains connected to the pressure-maintaining valve, no fresh breathing gas is supplied to the patient, which may lead to asphyxiation. Also in case the tracheal tube remains connected to the supply line for breathing gas, the pressure in the tracheal tube continues to linearly increase, which may lead to a bursting of the lungs. Consequently, known devices of this kind are disadvantageous and even dangerous.